This invention relates to sprinkler arrangements which are effective to protect stored documents while applying substantially lower volumes of water than conventional sprinkler arrangements.
Stored records such as libraries and archives containing paper documents and compilations contain valuable information which should be protected from damage by water to the extent possible while still assuring protection against fire damage. Many conventional fire protection arrangements for stored documents tend to apply excessive volumes of water which, while suppressing fire damage, results in significant water damage. While attempts have been made to control or reduce such water damage by generating a mist to control a fire, the very fine droplets constituting the mist produce a fog-like atmosphere which is not easily projected away from the mist generating nozzle and is often carried away from the fire by the fire plume before it can reach the location of the fire.
The Fishcer U.S. Pat. No. 5,839,667 discloses a water mist nozzle arrangement having a diffuser formed with tines which are bent away from the sprinkler body and are separated by channels formed in the surface of the diffuser facing the sprinkler body in which the sprinkler body has an orifice providing a K-factor in the range from about 0.1 to a maximum of 1.0.
Accordingly, it is an object of the present invention to provide a sprinkler arrangement for protecting stored documents which overcomes disadvantages of the prior art.
Another object of the invention is to provide a sprinkler arrangement which requires substantially less water than conventional sprinklers while effectively projecting a fire-smothering mist toward the location of a fire.
These and other objects of the invention are attained by providing a sprinkler arrangement which includes a sprinkler body with an axial passage for water and a deflector assembly positioned in spaced relation to the sprinkler body passage having two closely spaced substantially planar deflector members extending substantially perpendicular the axis of the passage. The deflector member closest to the sprinkler body passage has a plurality of openings to permit water to enter the space between the deflector members from which it is distributed in the form of a mist of very fine droplets while also distributing some of the impinging water in the form of larger fine droplets which are capable of penetrating the fire plume and carrying the mist toward the fire.
In a preferred embodiment the spacing between the peripheral edges of the two deflector members is in a range from about 0.001 inch to about 0.060 inch, preferably from about 0.020 inch to about 0.040 inch, and desirably about 0.030 inch. In this embodiment, the first deflector member has a plurality of radial slots extending inwardly from the outer periphery and the second deflector member has a recess in the surface facing the slots which tapers in the radially outward direction toward the space between the peripheral edges of the two deflector members. If desired, the second deflector member may also have a plurality of slots to permit larger fine droplets to emerge and carry very fine droplet mist generally in the axial direction of the sprinkler.